3 ms·

(Or, how to better organise a discreet relationship with the Director of the CIA.) from https://github.com/agl/pond https://github.com/agl/pond (the source) is

(Or, how to better organise a discreet relationship with the Director of the CIA.) from https://github.com/agl/pond https://github.com/agl/pond (the source) is a good elevator pitch, for people (like me) who are taking their time getting what this is. also, is code like this https://github.com/agl/pond/blob/master/server/server.go#L153 https://github.com/agl/pond/blob/master/server/server.go#L15... just extreme defensive programming? or is there some other reason for the check (eg is not everything locked)? also, does 2. A GPA can learn when messages are sent to a non-home server and which server that is. get weaker if there are many users? and why is it so quiet here? am i asking dumb questions? i've been deleting the ones i work out answers to!

agwa 13y ago
> also, is code like this https://github.com/agl/pond/blob/master/server/server.go#L153 https://github.com/agl/pond/blob/master/server/server.go#L15... just extreme defensive programming? or is there some other reason for the check (eg is not everything locked)? That's checking for integer overflow - an often-overlooked source of many security vulnerabilities. That's a signed integer though, and I don't know if signed integer overflow has defined behavior in Go. In C that would be undefined behavior, allowing the compiler to do potentially nutty things, so you would want to do the overflow check before the increment. (Edit: considering who the author of this code is, I would assume that Go has sane defined behavior on signed integer overflow ;-)
- packetslave 13y ago
  From the Go language spec: "For signed integers, the operations +, -, *, and << may legally overflow and the resulting value exists and is deterministically defined by the signed integer representation, the operation, and its operands. No exception is raised as a result of overflow. A compiler may not optimize code under the assumption that overflow does not occur. For instance, it may not assume that x < x + 1 is always true." func main() { var foo int8 = 127 fmt.Println(foo + 1) } prints -128
  - agwa 13y ago
    Cool, thanks for the info! Looking at the spec, I see that signed integers are elsewhere defined to be represented using 2's complement, so this is completely kosher.
kragen 13y ago
I think it's just that nobody knows the answers, mostly. HN is not great for questions that require thought. Also, btw, I still have your AMOP,a nd it would be awesome to see you again.
- andrewcooke 13y ago
  we've not visited argentina for years so we must be due a trip. if/when we do i'll ping you and you can give me that back during a meal at some nice restaurant...
  - kragen 13y ago
    awesome! :)

agwa 13y ago

> also, is code like this https://github.com/agl/pond/blob/master/server/server.go#L153 https://github.com/agl/pond/blob/master/server/server.go#L15... just extreme defensive programming? or is there some other reason for the check (eg is not everything locked)? That's checking for integer overflow - an often-overlooked source of many security vulnerabilities. That's a signed integer though, and I don't know if signed integer overflow has defined behavior in Go. In C that would be undefined behavior, allowing the compiler to do potentially nutty things, so you would want to do the overflow check before the increment. (Edit: considering who the author of this code is, I would assume that Go has sane defined behavior on signed integer overflow ;-)

packetslave 13y ago
From the Go language spec: "For signed integers, the operations +, -, *, and << may legally overflow and the resulting value exists and is deterministically defined by the signed integer representation, the operation, and its operands. No exception is raised as a result of overflow. A compiler may not optimize code under the assumption that overflow does not occur. For instance, it may not assume that x < x + 1 is always true." func main() { var foo int8 = 127 fmt.Println(foo + 1) } prints -128
- agwa 13y ago
  Cool, thanks for the info! Looking at the spec, I see that signed integers are elsewhere defined to be represented using 2's complement, so this is completely kosher.

kragen 13y ago

I think it's just that nobody knows the answers, mostly. HN is not great for questions that require thought. Also, btw, I still have your AMOP,a nd it would be awesome to see you again.

andrewcooke 13y ago
we've not visited argentina for years so we must be due a trip. if/when we do i'll ping you and you can give me that back during a meal at some nice restaurant...
- kragen 13y ago
  awesome! :)